THE nation has fallen silent to honour thousands of soldiers killed in the Battle of the Somme 100 years after the bloodiest day in British military history.

Ceremonies across the United Kingdom honoured the hundreds of thousands of victims of the brutal offensive which started in northern France on July 1, 1916.

The two-minute silence ended at 7.30am, the time when the British, Commonwealth and French forces went "over the top" a century ago.

The British Army suffered almost 60,000 casualties on the first day alone and more than a million men would be killed or wounded on both sides over the course of the 141-day offensive.

Taunton Deane MP, Rebecca Pow, paid tribute to those who fought, which included members of the Somerset Light Infantry.

She said: "100 years ago today, thousands of brave young men were alive in the morning, but had lost their lives by the time the sunset.

"It's important that we remember all of those young men who stood in the trenches, with no idea of what lay in wait.

"I observed my two minutes silence at 7.28am this morning in honour of them all.

"We must never forget what they sacrificed for us, we will always remember them."

The silence came after a night-long vigil led in Britain by the Queen and at the Thiepval Memorial to the Missing of theSomme, which towers over the rolling Picardy fields where so many fell.

Senior royals including the Duke and Duchess of Cornwall, the Duke and Duchess of Cambridge and Prince Harry, will join Prime Minister David Cameron and French President Francois Hollande and other leaders at the memorial later for a service of remembrance in front of an audience of 10,000.

In London, people lined Parliament Square to pay tribute, where the two-minute reflection was marked with the sound of gunfire.

People huddled under trees and umbrellas paused from their commutes to stand quietly.

The King's Troop Royal Horse Artillery were present, having been at Thiepval on Thursday night.

The soldiers manned three sets of guns, drawn into place by horses, and fired every four seconds for 100 seconds to mark the silence.

Whistles were blown and Big Ben chimed when the two minutes were over, though many still continued to pause in reflection.